System and method for coking detection

ABSTRACT

An improved system, apparatus and method may be configured for detecting coking in a gas turbine engine. The system may comprise one or more heatable collecting elements configured to be positioned in a fuel supply passage having an inlet and an outlet. The apparatus heatable collecting may be configured to generate heat at or over a fuel system temperature range to induce coking in at least one of the heatable collecting elements. The apparatus may also include a sensor configured to detect an indication of coking on the heatable collecting elements and, in response to the coking indication, communicate a coking condition signal to an engine control.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application claiming priority to U.S.patent application Ser. No. 15/171,579 filed Jun. 2, 2016, which isnon-provisional application claiming priority to U.S. ProvisionalApplication No. 62/171,301 filed Jun. 5, 2015, each of which is herebyincorporated by reference in its entirety.

FIELD OF TECHNOLOGY

An improved system for a gas turbine engine, and more specifically, afuel system having a coking sensor configured to detect an indication ofcoking including a build-up or accumulation of unwanted deposits such ascarbon.

BACKGROUND

Gas turbine engines typically include a compressor, a fuel system, acombustor, and a turbine. The compressor compresses air drawn into theengine and delivers high pressure air to the combustor. The fuel systemdelivers fuel such as liquid hydrocarbon fuel to the combustor, where itis mixed with the high pressure air and is ignited. Products of acombustion reaction in the combustor are directed into the turbine wherework is extracted to drive the compressor and, sometimes, an outputshaft. More specifically, combustors in gas turbine engines provide anenergy release that drives the turbine. This energy release takes theform of high temperature gases. The handling of these gases drives theoverall performance of the engine.

Recent advancements in such a gas turbine engine may use the liquidhydrocarbon fuel to cool hotter portions of the engine. In the processof cooling, the fuel can be heated to temperatures above the thermalstability limit of fuel, thereby resulting in the formation of cokingincluding gum, tar, and varnish deposits within the fuel system. Anapproach for preventing such deposits involves removing or reducing thedissolved oxygen normally found in untreated jet fuel as it flows intothe engine. Insufficient oxygen removal may occur due to failure ormiscalibration of the oxygen removal system. The safety and efficientoperation of a robustly engineered “hot fuel” system requires a means todetect such failure by measuring either oxygen concentration directly orthe formation of coke deposits caused by insufficient oxygen removal.Thus, detection of coking is crucial to the operation and maintenance ofgas turbine engines operating with fuel temperatures above thermalstability limits.

Traditional systems for measuring the percentage of entrained oxygen inthe liquid hydrocarbon fuels are unsuitable for aircraft applicationsdue to their size and weight. Further, typical systems may requireregular calibration and adjustment resulting in variable and unreliabledata outputs. Moreover, traditional systems do not provide an indicationof factors, other than oxygen, that influence fuel quality andcontribute to the coking of engine surfaces

Thus, there is a need for a system, apparatus, and method to detectcoking in fuel systems, e.g., that operate above the fuel thermalstability limit and rely on an oxygen removal device to reduceaccumulation of unwanted deposits such as carbon. Accordingly, thedetection of coking by this method may facilitate a change in engineoperating conditions to slow the coke deposition rate, or the timelymaintenance of the engine fuel system for removal of unwanted deposits,thereby increasing engine efficiency and reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

While the claims are not limited to a specific illustration, anappreciation of the various aspects is best gained through a discussionof various examples thereof. Referring now to the drawings, exemplaryillustrations are shown in detail. Although the drawings represent theillustrations, the drawings are not necessarily to scale and certainfeatures may be exaggerated to better illustrate and explain aninnovative aspect of an example. Further, the exemplary illustrationsdescribed herein are not intended to be exhaustive or otherwise limitingor restricted to the precise form and configuration shown in thedrawings and disclosed in the following detailed description. Exemplaryillustrations are described in detail by referring to the drawings asfollows:

FIG. 1 illustrates an exemplary gas turbine engine;

FIG. 2 illustrates an exemplary fuel system, for example, including afuel tank, a fuel stabilization system, a coking sensor system, a heatsource, a fuel system temperature sensor, and an engine control;

FIG. 3 illustrates an exemplary embodiment of a coking sensor system,for example, including one or more heatable collecting elements havingsurfaces configured to induce coking, and one or more pressure sensors;

FIG. 4 illustrates another exemplary embodiment of a coking sensorsystem, for example, including one or more heatable collecting elementshaving surfaces configured to induce coking, and an optical sensor;

FIG. 5 illustrates another exemplary embodiment of a coking sensorsystem, for example, including one or more heatable collecting elementshaving surfaces configured to induce coking, and a temperature sensor;

FIG. 6 illustrates another exemplary embodiment of a coking sensorsystem, for example, including one or more heatable collecting elementshaving surfaces configured to induce coking, and a proximity sensor; and

FIG. 7 illustrates another exemplary embodiment of a coking sensorsystem, for example, including one or more heatable collecting elementshaving surfaces configured to induce coking, and a vibration sensor.

For the purposes of promoting an understanding of the principles of theembodiments, reference will now be made to the embodiments illustratedin the drawings and specific language will be used to describe the same.It will nevertheless be understood that no limitation of the scope ofthe embodiments is thereby intended. Any alterations and furthermodifications in the described embodiments, and any further applicationsof the principles of the embodiments as described herein arecontemplated as would normally occur to one skilled in the art to whichthe embodiment relates.

DETAILED DESCRIPTION

An exemplary coking sensor system may be configured to induce and detectan indication of coking upstream of higher or maximum temperatureregions of the engine based on the downstream conditions. The higher ormaximum temperature regions may operate at temperatures above thethermal stability limit of fuel (e.g., liquid hydrocarbon fuel), therebyproducing coking in the engine fuel system at higher or maximumtemperature regions of the engine. The higher or maximum temperatureregions may include any heat source that may heat the fuel, e.g., anyportion of the engine that may raise the fuel temperature above itsthermal stability limit such as a heat exchanger, fuel cooled cooler, oranother hotter portion of the engine. Fuel systems may include a fuelstabilization system to reduce or eliminate coking. A fuel systemtemperature sensor may be configured to measure a fuel systemtemperature range near or downstream of the heat source and provide afuel system temperature signal to a coking sensor system upstream of theheat source. The coking sensor system may be configured to heat theupstream fuel to the fuel system temperature range, thereby inducingcoking conditions upstream of the heat source that are comparable to thedownstream coking conditions near or downstream of the heat source. Byimparting heat at the fuel system temperature range, the coking sensorsystem may detect an indication of coking upstream of the heat sourceand, in response to the coking condition, provide a coking conditionsignal to the engine control, thereby providing a notification to theengine control and allowing the engine control to take appropriateactions with respect to the coking indication.

An exemplary coking sensor system may include one or more heatablecollecting elements having one or more surfaces configured to inducecoking. The heatable collecting elements may be configured to bepositioned in a fuel supply passage having an inlet and an outlet. Theheatable collecting elements may be configured to generate heat at orover a range of fuel system temperature, e.g., to induce coking withrespect to the surfaces of the heatable collecting element. The heatablecollecting elements may be made with the same or similar materials andsurface finishes to those in the hotter portions of the fuel system, soas to replicate catalytic effects and induce coking upstream undercomparable conditions to those downstream in the engine. The system mayalso include a sensor configured to detect an indication of coking(e.g., physical build-up or accumulation of deposits) with respect to atleast one of the heatable collecting elements and, in response to thecoking indication, communicate a coking condition signal to an enginecontrol.

FIG. 1 illustrates a gas turbine engine 10, which includes a fan 12, alow pressure compressor 14, a high pressure compressor 16, a combustor18, a high pressure turbine 20, and a low pressure turbine 22. The highpressure compressor 16 is connected to a first rotor shaft 24 while thelow pressure compressor 14 is connected to a second rotor shaft 26. Theshafts 24, 26 extend axially and are parallel to an engine centerlineaxis 28. Ambient air 30 enters the fan 12 and is directed across a fanrotor 32 in an annular fan bypass duct 34, which in part iscircumscribed by nacelle 36. The bypass airflow 38 provides enginethrust while the primary gas stream 40 is directed to area 50 and intothe combustor 18 and the high pressure turbine 20. The fan nacelle 36 isspaced radially outwardly from the core casing 37 to define an annularbypass duct 34 therebetween. During operation, the core engine 11 powersthe fan 12 which pressurizes ambient air 30 to produce propulsion thrustin the fan air 38 bypassing the core engine 11 and discharged from thefan exhaust nozzle (not shown).

FIG. 2 illustrates a fuel system 100. Fuel system 100 may include a fueltank 102, a fuel stabilization system 104, a coking sensor system 106, afuel system temperature sensor 108, a fuel line 110, a heat source 112,and an engine control 114. The fuel stabilization system 104 may includea fuel treatment device configured to treat fuel and/or an oxygenremoval device configured to remove oxygen from fuel. The coking sensorsystem 106 may be positioned downstream of the fuel stabilization system104 and upstream or remote from heat source 112. Heat source 112 mayinclude any portion of the engine 10 that may raise the fuel temperatureabove its thermal stability limit such as a heat exchanger, fuel cooledcooler, or a hotter portion of the engine 10. It is appreciated that thefuel cooled cooler may utilize air, oil, refrigerant, any other heatcarrying fluid or material, or any combination thereof. Fuel from thefuel tank 102 may pass along the fuel stabilization system 104, cokingsensor system 106, heat source 112 (e.g., heating the fuel), and thefuel system temperature sensor 108. The fuel system temperature sensor108 may include a downstream sensor relative to coking sensor system106, e.g., positioned remote from coking sensor system 106 and at one ormore locations downstream of the coking sensor system 106 and near ordownstream of heat source 112. The fuel system temperature sensor 108may be configured to measure a fuel system temperature range (e.g., atemperature or a range of temperatures measured downstream of cokingsensor system 106 near or downstream of a higher or maximum temperatureregion of engine 10) of fuel system 100 and communicate the fuel systemtemperature range to the coking sensor system 106. With the measuredfuel system temperature range, the coking sensor system 106 may generateheat at or over the fuel system temperature range upstream of the heatsource 112, thereby inducing coking on one or more heatable collectingelements 216 under similar conditions to that experienced by thesurfaces of the engine 10 that are downstream of coking sensor system106, e.g., near or downstream of a higher or maximum temperature regionof engine 10. In response to detecting coking in the coking sensorsystem 106, the coking sensor system 106 may send a coking conditionsignal to the engine control 114, e.g., thereby providing a notificationof coking with respect to the downstream surfaces of engine 10.

FIG. 3 illustrates an exemplary embodiment of coking sensor system 106including coking sensor system 200. System 200 may include a fuel line202 having an inlet 204 and an outlet 206 forming a fuel passage, e.g.,a fuel supply passage. The fuel line 202 may include an inlet portion208 in fluid communication with the fuel stabilization system 104, asensor portion 210 configured to detect coking, and an outlet portion212 in fluid communication with the combustor 18. The sensor portion 210may be fixedly or removeably attachable with respect to the inlet andoutlet portions 208, 212, e.g., to facilitate access to or maintenanceof sensor portion 210. The system 200 may include one or a plurality ofheatable collecting elements 216, flow directing elements 214, andsensors 218.

The system 200 may be configured for measuring and detecting coking,e.g., thereby providing an advanced indication of impending cokingdownstream near a higher or maximum temperature region of engine 10. Anexemplary sensor 218 may include an upstream sensor as part of system200. Sensor 218 may include one or more pressure, optical, temperature,proximity, vibration, or impedance sensors or any combination thereofthat are configured to measure a parameter or a parameter change relatedto any of pressure, reflectivity, emissivity, temperature, distance,thickness, normal or resonant frequency, mass, or impedance orconductance. The system 200 may be configured to measure and detectcoking, e.g., thereby indicating near or downstream of a higher ormaximum temperature region of engine 10. Alternatively or in addition,sensor 218 may be part of or integrated into heatable collecting element216 and may be configured to provide heat and detect any of theparameters herein.

First and second heatable collecting elements 216 a, 216 b may bepositioned in the fuel line 202, e.g., a fuel supply passage of engine10. Flow directing element 214 may be disposed about the heatablecollecting elements 216 a, 216 b and may be configured to direct fuelflow along heatable collecting elements 216 a, 216 b. The heatablecollecting elements 216 a, 216 b may be configured to generate heat ator over the fuel system temperature range, e.g., to induce coking withrespect to at least one of the first and second heatable collectingelements 216 a, 216 b. Coking of the first and second heatablecollecting elements 216 a, 216 b, e.g., between and/or within flowdirecting elements 214, may increase the pressure differential betweenthe inlet and outlet of flow directing elements 214 a, 214 b. As such,sensor 218 may be configured to measure an indication of coking (e.g.,physical build-up or accumulation of deposits) on at least one of theheatable collecting elements 216 a, 216 b by measuring the pressuredifferential between sensor 218 a and 218 b and, in response to thecoking indication, communicate a coking condition signal to an enginecontrol 114. In addition, the coking sensor system 106 may be positionedin a primary flow area that receives a full fuel flow or a bypass flowarea that receives a partial fuel flow, e.g., to reduce the coolingprovided by the fuel flow to the one or more heatable elements 216thereby reducing the power required to heat the one or more heatableelements 216.

One or more heatable collecting elements 216 may betemperature-controlled and may include one or more surfaces (e.g., firstand second surfaces) that may be heated to induce coking formationthereon. Heatable collecting element 216 may be configured to generateheat to provide surface temperatures similar to those downstream of thecoking sensor system 106, e.g., near or downstream of a higher ormaximum temperature region of engine 10. For example, heatablecollecting element 216 may be configured to convert electricity intoheat through resistive heating. One or more heatable collecting elements216 may be configured as a wire or plate, which may be inserted into afuel line 110 a fuel system, e.g., a fuel supply line 202 of a “hotfuel” system.

Heatable collecting element 216 may be configured to facilitate thedetection of the onset of coking, e.g., by inducing the heat currentlybeing experienced near or downstream of a higher or maximum temperatureregion of engine 10. The heatable collecting element 216 may be heatedto a surface temperature that the flowing fuel is likely to encounterfurther downstream in the engine 10. The heatable collecting element 216may generate a surface temperature at a predefined heatable collectingset point that may be adjustable, e.g., in response to the fuel systemtemperature sensor 108 or temperatures measured during engine testing orstartup. The heatable collecting element 216 may include any materialand surface texture comparable to coke-prone surfaces of the “hot fuel”system, e.g., downstream of the coking sensor system 106. Thus, thesystem may be configured to detect the onset of coking upstream of thehigher or maximum temperature regions to preserve the engine surfacesdownstream of the coking sensor system 106, e.g., a fuel nozzle ofengine 10. Thus, one or more heatable collecting elements may generateheat at or over the fuel system temperature range, thereby inducingcoking on one or more heatable collecting elements 216 under similarconditions to that of the engine surfaces downstream of coking sensorsystem 106, e.g., near or downstream of a higher or maximum temperatureregion of engine 10.

Sensors 218 may be configured to detect an indication of coking (e.g.,physical build-up or accumulation of deposits) in response to measuredparameter or parameter change such as an increase or decrease relativeto a coking threshold, e.g., predefined parameter or range based onmeasurements taken prior to or during the start of engine operation toprovide a baseline for changes during operation. With further referenceto FIG. 3, system 200 may include sensor 218. The sensor 218 may includean inlet pressure sensor 218 b configured to measure an inlet staticpressure (Pi) with respect to the inlet 204, an element pressure sensor218 a configured to measure a sensor static pressure (Ps) with respectto at least one of the first and second heatable collecting elements 216a, 216 b, and an outlet pressure sensor 218 c (Po) configured to measurean outlet static pressure with respect to the outlet 206. Sensors 218are configured to detect coking in response to a measured changerelative to a baseline or threshold pressure, e.g., predefined toindicate coking. For example, coking may be detected according to thefollowing formula:

${\frac{{Ps} - {Pi}}{{Po} - {Pi}}{measured}} > {\frac{{Ps} - {Pi}}{{Po} - {Pi}}{baseline}}$Thus, sensor 218 may detect coking based on the relative pressurechange.

FIG. 4 illustrates another exemplary embodiment of a coking sensorsystem 200 including sensor 218, e.g., one or more optical sensors. Thesensor 218 may be in communication with light source 220. Light source220 may direct light beam toward and at an angle with respect to atleast one heatable collecting element 216. The heatable collectingelement 216 may reflect at least a portion of beam 222 to sensor 218.The heatable collecting element 216 may generate heat at or over thefuel system temperature range, e.g., thereby inducing coking on theheatable collecting element 216. Coking on the heatable collectingelement 216 may change the reflectivity or emissivity of its surface.Sensor 218 may measure the changes in beam 222 in response to the changein the surface of heatable collecting element 216 with respect to thecoking threshold, thereby detecting coking at coking sensor system 200,e.g., to indicate coking near or downstream of a higher or maximumtemperature region of engine 10. Accordingly, sensor 218 may detectcoking based on the reflectivity or emissivity change.

FIG. 5 illustrates another exemplary embodiment of a coking sensorsystem including sensor 218, e.g., a temperature sensor. The sensor 218may be embedded in or disposed on one or more heatable collectingelements 216. The heatable collecting element 216 may generate heat ator over the fuel system temperature range, e.g., thereby inducing cokingon the heatable collecting element 216. Coking 217 a, 217 b may build onthe surfaces of the heatable collecting element 216, e.g., therebyinsulating the heatable collecting element 216 from fuel passing throughfuel line 202. The sensor 218 may measure the relative temperatureincrease with respect to the coking threshold, thereby detecting cokingat coking sensor system 200, e.g., to indicate coking near or downstreamof a higher or maximum temperature region of engine 10. As a result,sensor 218 may detect coking based on the relative temperature change.

FIG. 6 illustrates another exemplary embodiment of a coking sensorsystem including sensor 218, e.g., a proximity sensor such as a laserproximity sensor. The sensor 218 may be embedded in or disposed on thefuel supply passage of fuel line 202. The heatable collecting element216 may generate heat at or over the fuel system temperature range,e.g., thereby inducing coking 217 a, 217 b on the surfaces of thecollecting element 216. Coking may build on the heatable collectingsurfaces 216, e.g., thereby increasing the thickness of and reducing thedistance between the collecting surface 216 and sensor 218.Alternatively or in addition, one or more additional sensors 218 may bepositioned at other locations along the fuel line 202, e.g., a secondsensor 218 on the opposite side of fuel line 202 and to measure cokebuilding on opposite surface of heatable collecting element 216. Thus, afirst parameter may be measured on a first surface of heatablecollecting surface 216 a and a second parameter may be measured on asecond surface of heatable collecting surface 216 b, which may be usedfor calibration of system 200 or redundant measurements to confirm theaccuracy of system 200. The sensor 218 may measure the distance decreasewith respect to the coking threshold, thereby detecting coking at cokingsensor system 200, e.g., to indicate coking near or downstream of ahigher or maximum temperature region of engine 10. Accordingly, sensor218 may detect coking based on the distance change.

FIG. 7 illustrates another exemplary embodiment of a coking sensorsystem including sensor 218, e.g., a vibration sensor such as anaccelerometer or transducer. The sensor 218 may be positioned relativeto at least one of the first and second heatable collecting elements 216a, 216 b. The heatable collecting element 216 may generate heat at orover the fuel system temperature range, e.g., thereby inducing coking onthe heatable collecting element 216. Coking 217 a, 217 b may build onthe heatable collecting surfaces of 216, e.g., thereby increasing themass of the collecting surfaces 216 a, 216 b and changing the natural orresonant frequency of the heatable collecting surfaces 216 a, 216 b inresponse to vibrational forces imparted by the fuel passing along fuelline 202 and over heatable collecting element 216. The sensor 218 maymeasure the relative frequency change with respect to the cokingthreshold, thereby detecting coking at the coking sensor system 200,e.g., to indicate coking near or downstream of a higher or maximumtemperature region of engine 10. As a result, sensor 218 may detectcoking based on the vibrational change.

Methods of operation are also contemplated. An exemplary method mayinclude providing at least one heatable collecting element 216 havingfirst and second surfaces. The method may further comprise measuring afuel system temperature range downstream of the at least one heatablecollecting element 216 using a downstream sensor 108, heating the atleast one heatable collecting element 216 to approximately the fuelsystem temperature range, detecting an indication of coking on at leastone of the first and second surfaces using an upstream sensor 218, andcommunicating a coking condition signal to the engine control 114.

In addition, methods of self-cleaning are also contemplated, e.g., aftercoking is detected and/or before the next operation of the engine 10.Air may be passed through the system 200 instead of fuel while theheatable collecting elements 116 are heated. The heatable collectingelements 116 may heat the coking deposits to a temperature sufficient toburn-off the carbon deposits. Thus, system 200 may be configured toperform self-cleaning.

The foregoing may provide a number of advantages. The coking sensorsystem 106 may provide improved accuracy over traditional systems. Forexample, the coking sensor system 106 may more directly measure thepressure, optical, temperature, proximity/thickness, and vibrationalchanges of the heatable collecting and/or collecting elements undercomparable conditions to engine surfaces in higher or maximumtemperature regions of the engine 10. Further, the coking sensor system106 may directly focus on the detection of coking instead of tangentialparameters such as fuel composition, thereby further enhancing accuracyover typical systems. Moreover, the coking sensor system 106 may bepositioned in an upstream location that may be more easily cleaned ormaintained, more easily accessed in the event of repair, removal, orreplacement, and more benign or thermally tolerable to sensors 218,e.g., remote from the higher or maximum temperature regions of theengine 10. In addition, coking sensor system 106 may provide cokingdetection for fuel systems such as hot fuel systems and may be used todetermine the effectiveness of oxygen removal systems.

The exemplary embodiments herein may be used in conjunction with anysystem of any vehicle including any engine system thereof. Merely asexamples, embodiments of the present disclosure may include or be usedin conjunction with any of the systems and methods disclosed in thecross-referenced disclosures mentioned above, which have beenincorporated herein.

It will be appreciated that the aforementioned method and devices may bemodified to have some components and steps removed, or may haveadditional components and steps added, all of which are deemed to bewithin the spirit of the present disclosure. Even though the presentdisclosure has been described in detail with reference to specificembodiments, it will be appreciated that the various modifications andchanges can be made to these embodiments without departing from thescope of the present disclosure as set forth in the claims. Thespecification and the drawings are to be regarded as an illustrativethought instead of merely restrictive thought.

What is claimed is:
 1. A system for coking detection in a gas turbineengine, comprising: at least one heatable collecting element having atleast one surface, the at least one heatable collecting elementpositioned in a fuel supply passage of a fuel system having an inlet andan outlet, and the at least one heatable collecting element beingconfigured to generate heat via resistive heating at or above a fuelsystem temperature range to induce coking on the at least one surfacethereby providing a catalytic effect on the at least one heatablecollecting element comparable to a downstream surface of the fuelsystem; and at least one flow directing element disposed about the atleast one heatable collecting element, structured and arranged to directfuel flow along the at least one surface of the at least one heatablecollecting element.
 2. The system of claim 1, further comprising asensor configured to detect an indication of coking on the at least oneheatable collecting element and, in response to the coking indication,communicate a coking condition signal to an engine control to at leastone of: adjust an operating condition of the gas turbine engine toreduce a deposition rate of the coking; and provide a notification formaintenance on the fuel system to remove the coking.
 3. The system ofclaim 1, further comprising a sensor that includes an inlet pressuresensor positioned with respect to the inlet, an element pressure sensorpositioned with respect to the at least one heatable collecting element,and an outlet pressure sensor positioned with respect to the outlet. 4.The system of claim 3, wherein the sensor is configured to detect thecoking indication based on a relative pressure increase of the elementpressure sensor relative to the inlet and outlet pressure sensors. 5.The system of claim 1, further comprising a sensor including at leastone of: an optical sensor in communication with a light source; atemperature sensor disposed in communication with the at least oneheatable collecting element; a proximity sensor positioned relative tothe fuel supply passage; and a vibration sensor positioned relative tothe at least one heatable collecting element.
 6. The system of claim 1,wherein the at least one surface of the at least one heatable collectingelement includes first and second surfaces, and the at least one flowdirecting element includes first and second flow directing elementscorresponding to the respective first and second surfaces of the atleast one heatable collecting element.
 7. The system of claim 1, whereinthe at least one heatable collecting element is configured as aresistance heating wire or plate.
 8. A method of coking detection for agas turbine engine, comprising; providing at least one heatablecollecting element having at least one surface configured to bepositioned in a fuel supply passage of a fuel system having an inlet andan outlet; measuring a fuel system temperature range downstream of theat least one heatable collecting element; heating the at least oneheatable collecting element via resistive heating to approximately thefuel system temperature range thereby providing a catalytic effect onthe at least one heatable collecting element comparable to a downstreamsurface of the fuel system; detecting an indication of coking on the atleast one surface of the at least one heatable collecting element; andcommunicating, in response to the coking indication, a coking conditionsignal to an engine control.
 9. The method of claim 8, furthercomprising a first sensing downstream of the at least one heatablecollecting element as part of the measuring of the fuel systemtemperature range, and a second sensing upstream of the at least oneheatable collecting element as part of the detecting of the indicationof coking.
 10. The method of claim 9, wherein the first sensing includespressure sensing adjacent at least one of the inlet, the at least oneheatable collecting element, and the outlet.
 11. The method of claim 10,further comprising detecting, by the upstream sensor, the cokingindication based on a relative pressure increase between the inlet andoutlet.
 12. The method of claim 9, further comprising at least one ofoptically sensing, temperature sensing, proximity sensing, and vibrationsensing adjacent the at least one heatable collecting element.
 13. Themethod of claim 8, further comprising directing flow to the at least onesurface of the at least one heatable collecting element by positioningat least one flow directing element about the at least one heatablecollecting element.
 14. The method of claim 8, further comprisingdirecting flow along first and second surfaces of the at least oneheatable collecting element by positioning first and second flowdirecting elements relative to the first and second surfaces of the atleast one heatable collecting element.
 15. A system for cokingdetection, comprising: a fuel supply passage of a fuel system having aninlet and an outlet; at least one heatable collecting element having atleast one surface positioned in the fuel supply passage, the at leastone heatable collecting element being configured to generate heat viaresistive heating at or above a fuel system temperature range to inducecoking on the at least one surface of the at least one heatablecollecting element thereby providing a catalytic effect comparable to adownstream surface of the fuel system; and a sensor configured to detectan indication of coking on the at least one heatable collecting elementand, in response to the coking indication, communicate a cokingcondition signal to an engine control.
 16. The system of claim 15,wherein the sensor includes an inlet pressure sensor positioned withrespect to the inlet, an element pressure sensor positioned with respectto the at least one heatable collecting element, and an outlet pressuresensor positioned with respect to the outlet.
 17. The system of claim16, wherein the sensor is configured to detect the coking indicationbased on a relative pressure increase of the element pressure sensorrelative to the inlet and outlet pressure sensors.
 18. The system ofclaim 15, wherein the sensor includes at least one of: an optical sensorin communication with a light source; a temperature sensor disposed inthe at least one heatable collecting element; a proximity sensorpositioned relative to the fuel supply passage; and a vibration sensorpositioned relative to the at least one heatable collecting element. 19.The system of claim 15, wherein the at least one heatable collectingelement includes first and second surfaces, and further comprising atleast one flow directing element disposed about the first and secondsurfaces of the at least one heatable collecting element.